Lachin J M, Foulkes M A
Biometrics. 1986 Sep;42(3):507-19.
When designing a clinical trial to test the equality of survival distributions for two treatment groups, the usual assumptions are exponential survival, uniform patient entry, full compliance, and censoring only administratively at the end of the trial. Various authors have presented methods for estimation of sample size or power under these assumptions, some of which allow for an R-year accrual period with T total years of study, T greater than R. The method of Lachin (1981, Controlled Clinical Trials 2, 93-113) is extended to allow for cases where patients enter the trial in a nonuniform manner over time, patients may exit from the trial due to loss to follow-up (other than administrative), other patients may continue follow-up although failing to comply with the treatment regimen, and a stratified analysis may be planned according to one or more prognostic covariates.
在设计一项临床试验以检验两个治疗组生存分布的相等性时，通常的假设是指数生存、患者均匀入组、完全依从以及仅在试验结束时进行管理性删失。许多作者已经提出了在这些假设下估计样本量或检验效能的方法，其中一些方法允许有一个R年的入组期，总研究时间为T年，T大于R。拉钦（1981年，《对照临床试验》2，93 - 113）的方法得到了扩展，以适用于患者随时间非均匀入组、患者可能因失访（而非管理性原因）退出试验、其他患者尽管未遵守治疗方案仍继续随访的情况，并且可以根据一个或多个预后协变量计划进行分层分析。
